A server that manages a plurality of printers is well known in the art. With conventional technology, each of the printers transmits data including the residual quantities of toner in their cartridges to the server. When the residual quantity of toner in a cartridge mounted in one of the printers drops to a threshold value or below, the server sets the cartridge as a supply target (a target for replacement). The server then estimates the timings at which replacement cartridges must be supplied for cartridges other than the cartridge set as the supply target. If the estimated timing for any cartridge other than the supply target is within three days of the current date, the server adds these cartridges as supply targets.